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PubMed2007

How to tweak a beak: molecular techniques for studying the evolution of size and shape in Darwin's finches and other birds.

A flurry of technological advances in molecular, cellular and developmental biology during the past decade has provided a clearer understanding of mechanisms underlying phenotypic diversification. Building upon such momentum, a recent paper tackles one of the foremost topics in evolution, that is the origin of species-specific beak morphology in Darwin's finches.1 Previous work involving both domesticated and wild birds implicated a well-known signaling pathway (i.e. bone morphogenetic proteins) and one population of progenitor cells in particular (i.e. cranial neural crest), as primary factors for establishing beak size and shape. But these results were limited in their ability to explain fully the morphogenetic bases of patterned outgrowth. So in a quest to identify novel genes whose expression correlated with differences in beak anatomy among Darwin's finches, a DNA microarray approach was undertaken using tissues harvested from the Galápagos Islands. The results are striking and point to a protein called calmodulin, which is a mediator of cellular calcium signaling, as a key determinant of beak length.

Animals↗
PubMed2004

The effect of claw and beak reduction on growth parameters and fearfulness of two Leghorn strains.

Commercial equipment used by the turkey industry at hatch sterilizes the germinal tissue of the claw with microwave energy and the beak tissue with infrared energy. This effectively trims the claws and beaks of the birds. Two strains of Leghorn chicks (1,200 each strain) were utilized to test this technique on chickens. Half were subjected to the claw reduction (RC) technique at hatch, and half retained intact claws (IC). The beaks of one-third of the birds in the claw treatments were reduced (BT) at hatch using the infrared technique, one-third were precision trimmed at 7 d, and one-third were not trimmed (IB). Body weight, weight gain, feed intake, feed conversion, mortality, and fearfulness were measured. Rearing followed standard commercial feeding and husbandry procedures. The RC birds had significantly lower BW, except from 3 to 6 wk, and had significantly lower feed consumption from 8 to 18 wk. The 1 d BT birds experienced significantly lower BW from 3 to 14 wk and ate less total feed by 4 wk. Mortality was less than 2.1% for all treatments. From 6 to 8 wk, fearfulness score (a subjective scale of 1 to 10) peaked at 8 to 10 for IC birds and 3 to 4 for RC birds. By 16 to 18 wk, fearfulness score subsided to 2 to 3 for RC and 6 to 8 for IC. Beak trimming and reduction of claw growth at hatch allowed pullets to be grown to sexual maturity on less feed and with a lower level of observed fearfulness using standard husbandry practices.

Agriculture↗
PubMed1984

The pathology of psittacine beak and feather disease.

Psittacine beak and feather disease is characterised by loss of feathers, abnormally shaped feathers and overgrowth and irregularity of the surface of the beak. The disease occurs in a number of psittacine species including the Sulphur-crested Cockatoo, Lovebirds , Budgerigars and Galahs . The abnormal appearance of feathers and beak is due to a dystrophic process within the epidermis of the feather and beak. The process consists of epidermal cell necrosis, epidermal hyperplasia and hyperkeratosis. Many of the feather abnormalities are due to retention of a hyperkeratotic feather sheath. A characteristic microscopic finding is the presence of macrophages containing purple intracytoplasmic inclusions in affected epidermis and feather pulp. The inclusions consist of aggregates of particles 17 to 22 nm in diameter. Similar but smaller inclusions occur in epidermal cells. In addition, non-suppurative inflammation occurs in the feather pulp. The findings are suggestive of a viral infection.

Animals↗
PubMed2004

Bmp4 and morphological variation of beaks in Darwin's finches.

Darwin's finches are a classic example of species diversification by natural selection. Their impressive variation in beak morphology is associated with the exploitation of a variety of ecological niches, but its developmental basis is unknown. We performed a comparative analysis of expression patterns of various growth factors in species comprising the genus Geospiza. We found that expression of Bmp4 in the mesenchyme of the upper beaks strongly correlated with deep and broad beak morphology. When misexpressed in chicken embryos, Bmp4 caused morphological transformations paralleling the beak morphology of the large ground finch G. magnirostris.

Animals↗
PubMed2004

Molecular shaping of the beak.

Beak shape is a classic example of evolutionary diversification. Beak development in chicken and duck was used to examine morphological variations among avian species. There is only one proliferative zone in the frontonasal mass of chickens, but two in ducks. These growth zones are associated with bone morphogenetic protein 4 (BMP4) activity. By "tinkering" with BMP4 in beak prominences, the shapes of the chicken beak can be modulated.

Animals↗
PubMedDate not supplied

Bacteria associated with beak necrosis in broiler breeder hens.

Beak necrosis occurred in 48 per cent of female broiler breeders used fro nutritional studies but none was found in male broiler breeders or in either sex of single comb white Leghorns. About 10 per cent mortality, probably largely due to beak necroses, occurred in the affected flock. Based on electron microscopic photographs of affected beak tissue, we suggest that in our study the breakdown of beaks was associated with the presence of a single morphological type of Gram-positive bacterium.

Animals↗
PubMed1984

Behavior and growth parameters of large white turkeys as affected by floor space and beak trimming. 1. Males.

The effects of floor space and beak trimming on behavior and growth of Large White male turkeys were investigated Floor space allowances were 6.5, 9.3, and 12.1 dm2/bird at 0 to 8 weeks; 11.7, 16.7, and 21.8 dm3/bird at 8 to 12 weeks; and 28, 35, and 42 dm3/bird at 12 to 20 weeks. Floor space was adjusted by changing the pen size while maintaining a constant number of birds per pen. Body weight, feed intake, feed efficiency, feather score, live market quality, and mortality were measured. In addition, agonistic behavior including "threat avoids", "peck avoids", "threat chases", "peck chases" and "fights", and nonagonistic behavior including feather "pecks" and "pecks and pulls" were determined at 12 and 20 weeks of age. Floor space had no significant effect on any parameter measured through 8 weeks. At 12 weeks, feed efficiency and body weight were significantly decreased with decreasing floor space. By 20 weeks, the body weight of the birds grown at the intermediate floor space allowance from 8 to 12 weeks was no longer significantly different from those grown at the highest floor space allowance; however, the birds grown at the highest density from 8 to 12 weeks remained significantly lighter at 20 weeks. Compensatory growth, if present, appeared limited. Beak trimming had no significant effect on body weight or feed efficiency. Food intake was significantly greater in the beak trimmed birds from 12 to 18, but there was no significant difference from 12 to 20 weeks. From 12 to 20 weeks, mortality was significantly less in beak-trimmed birds.(ABSTRACT TRUNCATED AT 250 WORDS)

Aggression↗
PubMed1985

Behavior and growth parameters of large white turkeys as affected by floor space and beak trimming. II. Females.

The effects of floor space allowance and beak trimming on behavior and growth performance of female Large White turkeys were studied. Floor space allowances were 5.6, 7.0, and 9.3 dm2/bird from 0 to 8 weeks of age and 14.0, 18.6, and 23.2 dm2/bird from 8 to 16 weeks of age. Floor space was adjusted by changing pen size to assure a constant number of birds per pen. Results showed that neither floor space allowance nor beak trimming had any significant effect of any of the variables under study through 8 weeks of age. At 16 weeks of age, growth, feed consumption, feed efficiency, feather scores, live market quality grades, and mortality were still unaffected. Beak trimming significantly reduced body weight gain, body weight, and feed consumption but had no significant effect on feed efficiency, feather scores, or mortality. Agonistic (aggressive) behavior was very low in this population of females. Of significance, however, were the nonaggressive behaviors of social "pecking" and "pecking and pulling" of feathers. Feather-pecking activity was unaffected by previous or subsequent floor space allowances through 16 weeks of age; however, the incidence of pecking and pulling of feathers was highest among females previously assigned the largest floor space allowance (9.3 dm2/bird) in the brooder house and subsequently allowed the smallest floor space allowance (14.0 dm2/bird) in the grower house. Beak trimming significantly increased the frequency of both "pecking" and "pecking and pulling" of feathers over that of their untrimmed contemporaries when the females were 12 and 16 weeks of age. Possible reasons for this are discussed.

Aggression↗
PubMed1992

Research note: effects of beak trimming and genetic stock on rate of mash consumption and feeding-related behavior in egg-strain pullets.

Pullets whose beaks were trimmed once (at 9 days) and twice (at 9 days and 9 wk) were able to ingest feed, in the form of mash, more rapidly under competitive feeding conditions and at least as rapidly in the absence of competition as pullets with intact beaks. Tests of feeding rate, when pullets fed in groups, were carried out after a feed deprivation period of 7 h at ages of 10 through 16 wk. Similar tests were done at 18 wk, when pullets fed without competition. Genetic stock and age had significant effects on frequency of agonistic acts at the feeder and displacements from the feeder during 5-min tests under competitive feeding conditions. Age influenced the number of pullets feeding simultaneously and amount of feed eaten per pullet during the same feeding tests. No interactions were detected among beak treatment, stock, and age for feeding-related behaviors or rate of feed consumption during competitive feeding. In noncompetitive feeding tests, genetic stock affected feeding rate but no stock by beak treatment interaction was present.

Aging↗
PubMed1984

Beak and feather dystrophy in wild sulphur-crested cockatoos (Cacatua galerita).

Three flocks of wild sulphur-crested cockatoos in southeastern Australia had a 10-20% prevalence of feather and beak deformities. In affected birds, the crest, tail, contour and down feathers were lost or reduced in length owing to a "pinching off" 0.5-1 cm above the skin. The underlying skin was discolored brown. Flight feathers appeared normal and could sustain flight. In mildly affected birds, only the crest and down feathers were involved. Histological examination of affected feathers showed necrosis of developing cells in their epidermal collars. The epidermis was moderately hyperplastic and contained numerous large macrophages, with large intracytoplasmic granules. Electron microscopic examination showed these granules to consist of regular lattices of 17-20-nm-diameter particles, resembling parvovirus particles. In some birds the upper beak was enlarged and had longitudinal cracks. Histological examination of the beak showed necrosis of its epidermis. It was concluded that a viral infection may have caused feather and beak dystrophy in these birds.

Animals↗
PubMed1976

The influence of propanediol-1,3 on the development of the legs, wings and lower beak of the chick embryo.

In seven series of 31-34 chick embryos each, the influence of the position of the egg during incubation and of the administration of 0.05 ml propanediol-1,3 on the 5th day of incubation on the development and growth of the limbs and beak were studied. Isotonic saline injected embryos served as controls. The embryos were sacrificed at the age of 15 days. Incubation of the egg in a vertical position, with the air chamber pointing upward, proved to result in a slight, through significant reduction in the length of the limbs and beak. Propanediol was highly toxic if injected in the immediate vicinity of the embryo. If injected at some distance from the embryo, either into the air chamber or into the yolk, the agent proved to be teratogenic: measurements showed a considerable retardation of the longitudinal growth of the limbs and beak, the latter being a parrot beak in 60 per cent of the cases, whereas both the tibia and the metatarsals were, moreover, bent posteriorward. Histological studies of the tibia showed an underdevelopment of the periosteal bone collar and, at the angle of the bone, a replacement of the posterior part of this collar by endochondral bone trabeculae. The abnormalities observed are dissimilar to those demonstrated in hereditary congenital chondrodystrophy and in micromelic conditions induced by insulin or sulfonamides.

Animals↗
PubMed1984

Analysis of upper beak defects in chicken embryos following with retinoic acid.

Implanting inert carriers soaked in retinoic acid into the anterior margin of the developing limb of chicken embryos leads to orofacial malformations as well as affecting pattern formation in the limb. Using anion-exchange beads as carriers, and soaking solutions of 1-10 mg/ml retinoic acid, almost 100% of the embryos have malformations of the face. The effects on the treated limbs range from symmetrical patterns of duplicated digits (maximum number of digits being four) to truncations in which no digits were formed at all. Typically, in the malformed faces the upper beak is completely absent, no nostrils are present and the front of the face forms a scalloped rim of tissue above the mouth. By reference to normal beak development, the seven bulges of tissue that make up the rim can be identified as derivatives of the masses of tissue that normally would fuse to form the upper beak. The roof of the mouth consists of three bulges of tissue flanked by widely separated palatal shelves. The defect can thus be classified as severe bilateral clefting of the primary palate. By examining the morphology of the faces of treated embryos, the origin of the defect can be traced to failure of the frontonasal mass to enlarge. Thus, the oronasal fissures are very wide and fusion across them to form the primary palate cannot occur. The way in which retinoic acid brings about the defect is discussed in relation to possible mechanisms involved in the production of cleft palate. The parallel is noted between the associated effects of retinoic acid on beak and limb morphogenesis and the chick mutation cpp, that also affects both face and limbs.

Abnormalities, Drug-Induced↗
PubMed1975

Development of beaks of Rana pipiens larvae.

Rana pipiens larval beaks of consist of column cells, sheath cells and basal cells which supply cells to column and sheath. Each column consists of disk-like precone cells, cone cells and keratinized cone cells; they are cells in different stages of the process of keratinization. Breaks first appear externally at embryonic stage 24. Epidermal cells align at the tip of the jaw at stage 21. They increase in number and change in shape. Keratinization starts at stage 23. By stage 24, the apical column cells are keratinized and the histological organization is set for the whole larval period. During the larval period, the numbers of column cells increase until stages VIII or IV, stay relatively constant during mid-larval stages, and decrease at late larval stages. The beak is completely shed at stage XX. The widening of the beaks goes on during the entire larval period. Along the cutting edge of the jaw the tooth spikes increase in number and in individual width as the animal grows older and larger. Thyroid hormone causes a premature reduction of the column cell number and a precocious beak loss. The loss of break at metamorphic climax is thyroid dependent event.

Animals↗
PubMed2004

Degree of tectal beaking correlates to the presence of nystagmus in children with Chiari II malformation.

INTRODUCTION: Tectal beaking is a common finding in children born with a myelomeningocele. Quantitation of the presence or absence of this finding correlated with normal or abnormal eye movements is lacking in the medical literature. MATERIALS AND METHODS: We prospectively evaluated 50 children in our multidisciplinary spina bifida clinic. Each child was observed for the presence or absence of nystagmus at rest or with extraocular movement. Grades of nystagmus and severity of tectal beaking (Types I-III) on MRI were then correlated. RESULTS: Overwhelmingly, children with greater dysmorphology of the mesencephalic tectum were most likely to have nystagmus. Higher grades of nystagmus were associated with Type III tectal beaking. CONCLUSIONS: We have demonstrated that there is a correlation between the presence and severity of nystagmus and the severity of tectal beaking and have quantified this association in patients with the Chiari II malformation. This information may act as a guide in predicting which children with the Chiari II malformation will have significant nystagmus. These data may aid the clinician in the interpretation of oculomotor abnormalities in this cohort of patients.

Adolescent↗
PubMed1993

Contact patterns in the trapeziometacarpal joint: the role of the palmar beak ligament.

Twenty-three cadaver forearm specimens were mounted on a Plexiglas acrylic plastic base for study of the trapeziometacarpal joint. Extrinsic and intrinsic motors were loaded to simulate lateral pinch, and pressure-sensitive film was used to record joint contact patterns in various functional positions. The palmar compartment of the trapeziometacarpal joint was the primary contact area during flexion adduction of the thumb ray in lateral pinch. Simulation of dynamic pinch and release produced dorsal enlargement of the contact pattern, suggesting physiologic translation of the metacarpal on the trapezium. Detachment of the palmar beak ligament resulted in dorsal translation of the contact area, producing a pattern similar to that of cartilage degeneration seen in the osteoarthritic joint. End-stage osteoarthritic specimens had a nonfunctional beak ligament and demonstrated a pathologic total contact pattern of joint congruity that was unaffected by further manipulations of the beak ligament. This work defines the contact patterns in the normal and diseased trapeziometacarpal joint and establishes the important influence of the palmar beak ligament on those contact areas.

Cartilage Diseases↗
PubMed2004

Estimated transmission beam pattern of clicks recorded from free-ranging white-beaked dolphins (Lagenorhynchus albirostris).

Recordings were made from white-beaked dolphins in Icelandic waters using a four-hydrophone array in a star configuration. The acoustic signals were amplified and sampled to a hard disk at a rate of 800 kHz per channel. The 3 and 10 dB beamwidths were calculated to be 8 degrees and 10 degrees, respectively, indicating a narrower transmission beam for white-beaked dolphins than that reported for bottlenose dolphins (Tursiops truncatus). The beamwidth was more similar to that found for belugas (Delphinapterus lucas). The measured beam pattern included large side lobes, perhaps due to the inclusion of off-axis clicks, even after applying several criteria to select only on-axis clicks. The directivity index was calculated to be 18 dB when using all data for angles from 0 degrees-50 degrees. The calculated sound radiation from a circular piston with a radius of 6 cm driven by a white-beaked dolphin click had a beam pattern very similar to the measured beam pattern for the main transmission lobe of the white-beaked dolphin. The directivity index was 29 dB. This is the first attempt to estimate the directionality index of dolphins in the field.

Acoustic Stimulation↗
PubMed2006

Extreme diving of beaked whales.

Sound-and-orientation recording tags (DTAGs) were used to study 10 beaked whales of two poorly known species, Ziphius cavirostris (Zc) and Mesoplodon densirostris (Md). Acoustic behaviour in the deep foraging dives performed by both species (Zc: 28 dives by seven individuals; Md: 16 dives by three individuals) shows that they hunt by echolocation in deep water between 222 and 1885 m, attempting to capture about 30 prey/dive. This food source is so deep that the average foraging dives were deeper (Zc: 1070 m; Md: 835 m) and longer (Zc: 58 min; Md: 47 min) than reported for any other air-breathing species. A series of shallower dives, containing no indications of foraging, followed most deep foraging dives. The average interval between deep foraging dives was 63 min for Zc and 92 min for Md. This long an interval may be required for beaked whales to recover from an oxygen debt accrued in the deep foraging dives, which last about twice the estimated aerobic dive limit. Recent reports of gas emboli in beaked whales stranded during naval sonar exercises have led to the hypothesis that their deep-diving may make them especially vulnerable to decompression. Using current models of breath-hold diving, we infer that their natural diving behaviour is inconsistent with known problems of acute nitrogen supersaturation and embolism. If the assumptions of these models are correct for beaked whales, then possible decompression problems are more likely to result from an abnormal behavioural response to sonar.

Activity Cycles↗
PubMed2026

First molecular detection and partial ORF1 characterization of psittacine beak and feather disease virus (PBFDV) in domesticated parrots of Northern Vietnam.

Psittacine beak and feather disease virus (PBFDV), currently classified within the species Circovirus parrot, is an infectious agent in avian species, particularly psittacine birds. PBFDV is the causative agent of psittacine beak and feather disease (PBFD), leading to feather loss, deformed beaks and nails, immunosuppression, and high mortality. However, there is limited information on PBFDV in Vietnam, particularly in domesticated parrots. This study aims to detect and molecularly characterize PBFDV in psittacine birds in Northern Vietnam. Among the 193 psittacine birds tested by conventional PCR, 48 were PBFDV-positive, corresponding to a positivity rate of 24.87%. Based on partial ORF1 characterization, phylogenetic tree analysis of the ten PBFDV sequences showed that genotype I, which exhibits genetic diversity, is circulating in Vietnam. This study highlights the importance of genomic characterization of PBFDV in domesticated exotic psittacine birds in Vietnam. Together with the recent cases of PBFD in domestic parrots, further surveillance is needed to elucidate the host specificity, transmission, and pathophysiology of PBFDV.

Animals↗